class_docstr: TTS abstract class.
docstr: Calculate outputs and return the loss tensor.
docstr_tok: ["Calculate","outputs","and","return","the","loss","tensor","."]
code: def forward(
      self,
      input_states: torch.Tensor,
      input_states_lengths: torch.Tensor,
      feats: torch.Tensor,
      feats_lengths: torch.Tensor,
      **kwargs,
  ) -> Tuple[torch.Tensor, Dict[str, torch.Tensor], torch.Tensor]:
      """Calculate outputs and return the loss tensor."""
      raise NotImplementedError
  
file_path: espnet/espnet2/s2st/synthesizer/abs_synthesizer.py
imports: from abc import ABC, abstractmethod
  from typing import Dict, Tuple
  import torch
label_desc: Use image node_id 1 for calling the AbsSynthesizer obj's underlying member method code with example usage: obj.forward(input_states, input_states_lengths, feats, feats_lengths) without return types